Whereas ligation of CD28 is known to provide a critical costimulatory signal for activation of CD4 T cells, the requirement for CD28 as a costimulatory signal during activation of CD8 cells is less well defined. Even less is known about the involvement of CD28 signals during peripheral tolerance induction in CD8 T cells. In this study, comparison of T cell responses from CD28-deficient and CD28...

Zwitterionic capsular polysaccharides (ZPS) of commensal bacteria are characterized by having both positive and negative charged substituents on each repeating unit of a highly repetitive structure that has an alpha-helix configuration. In this paper we look at the immune response of CD8(+) T cells to ZPSs. Intraperitoneal application of the ZPS Sp1 from Streptococcus pneumoniae serotype 1 indu...

OBJECTIVE Immune thrombocytopenic purpura (ITP) is an immune-mediated bleeding disorder in which platelets are opsonized by autoantibodies and destroyed by an Fc receptor-mediated phagocytosis by the reticuloendothelial system within the spleen. Autoimmune processes are also considered in the pathogenesis of this disorder. CD4+CD25+FoxP3+ regulatory T (Treg) cells and CD8+CD28- Treg cells have ...

CD8(+) T cells are a critical component of the adaptive immune response against infections and tumors. A current paradigm in immunology is that naive CD8(+) T cells require CD28 costimulation, whereas memory CD8(+) T cells do not. We show here, however, that during viral infections of mice, costimulation is required in vivo for the reactivation of memory CD8(+) T cells. In the absence of CD28 c...

BACKGROUND Lack of CD28 expression on peripheral blood CD4+ and CD8+ T cells has been reported in patients with Wegener's granulomatosis (WG), suggesting a pathogenetic role of CD28- T cells in WG. METHODS Ten patients with WG and six with sarcoidosis (disease control) were analysed. Fluorescence activated cell sorter (FACS) analysis was used to detect CD28 expression on T cells from peripher...

The lymphocytic choriomeningitis virus (LCMV) system constitutes one of the most widely used models for the study of infectious disease and the regulation of virus-specific T cell immunity. However, with respect to the activity of costimulatory and associated regulatory pathways, LCMV-specific T cell responses have long been regarded as relatively independent and thus distinct from the regulati...

The relationship between the number of circulating CD4+ T cells and the presence of particular CD8+ T cell subsets was analyzed by flow cytometry on PBL from asymptomatic HIV-1-infected patients whose specimens were collected every 2 mo for a total period of 32 mo. Only slight variations were detected in the absolute number of lymphocytes and percentage of CD3+ lymphocytes, whereas both CD4+ an...

Infectious mononucleosis (IM) is an acute sporadic infection that usually affects young adults, and during infection a massive expansion of CD8 T cells is generally considered to occur. However, CD28 expression of the expanded cells has not been characterized. When peripheral blood mononuclear cells of acute IM (AIM) patients were analyzed by flow cytometry, a continuous spectrum of CD28 intens...

Because the chemokine receptor CCR5 is expressed on Th1 CD4(+) cells, it is important to investigate the expression and function of this receptor on other T cells involved in Th1 immune responses, such as Ag-specific CD8(+) T cells, which to date have been only partially characterized. Therefore, we analyzed the expression and function of CCR5 on virus-specific CD8+ T cells identified by HLA cl...